How a Company in Brussels Solved Spending 15+ Hours Weekly Collecting Customer Reviews Manually Using OpenAI Agents

Manual collection of customer reviews can be an incredibly time-consuming task for any company aiming to boost its online reputation and improve service quality. 📊 In Brussels, a growing SaaS startup was spending over 15 hours per week just gathering customer feedback — a process fraught with inefficiencies and delays. This case study explores exactly how automation using OpenAI Agents empowered this company to save time, reduce errors, and enhance visibility on customer sentiment.

In this article, you will discover the client’s initial manual process challenges, RestFlow’s tailored automation proposal, the technical architecture powered by n8n integrated with Gmail, Google Sheets, and HubSpot, and the concrete measurable business outcomes they achieved. We’ll also cover detailed workflow steps, error handling, scaling strategies, and key points to consider when implementing AI-driven automation in customer feedback collection.

If you’re a startup CTO, automation engineer, or operations specialist looking to automate repetitive tasks, this realistic success story with hands-on insights will inspire your next automation project.

The Problem: Time-Consuming Manual Customer Review Collection in Brussels

The client is a SaaS startup based in Brussels, Belgium, operating in the technology sector. Their Customer Success and Marketing departments were tasked with collecting customer reviews across different platforms manually — a crucial yet manual and fragmented process.

Initial Process:

• Manually gathering reviews from emails, social media mentions, and direct customer feedback forms.
• Copy-pasting reviews into Google Sheets for aggregation.
• Manually identifying sentiment and categorizing reviews for marketing use.
• Sending personalized thank-you emails to reviewers.

Pain Points:

• More than 15 hours per week spent manually collating reviews — over 60 hours monthly wasted on low-value manual work.
• High risk of missing reviews or duplicating entries due to human error.
• Delayed responses to customers due to slow processing.
• Lack of centralized dashboard for visibility: Marketing and Customer Success lacked real-time tracking of review status.
• Data inconsistency across platforms affecting marketing campaigns and product improvement insights.

This inefficiency directly impacted customer engagement metrics and slowed down decision-making, limiting the company’s ability to act on feedback promptly and improve its public rating — a key growth driver in SaaS markets.

Our Approach: Mapping and Designing a Streamlined Automation Solution

RestFlow commenced with a detailed discovery phase, collaborating with client stakeholders from Operations, Marketing, and IT departments. The goal was to fully understand the existing workflows, pain points, and system landscape.

Process Mapping & Analysis:

• Documented each manual step of the review collection and processing efforts.
• Identified key data sources: Gmail inbox, Google Forms, social media platforms accessed via HubSpot CRM.
• Noted current use of Google Sheets for manual tracking and email templates for thank-you responses.
• Recognized redundant manual data entry and lack of orchestration between tools.

Technology Selection:

Based on client preferences and their need for scalability and flexibility, RestFlow recommended using n8n as the core orchestrator for its open-source nature, powerful workflow capabilities, and seamless integrations with the existing tools:

• Gmail for email triggers and sending automatic replies.
• Google Sheets as a centralized repository for all customer reviews.
• HubSpot CRM for customer data enrichment and tracking marketing campaigns.
• OpenAI Agents for automated sentiment analysis, categorization, and response drafting.

This setup was designed for efficiency, error reduction, and enhancing team productivity. RestFlow delivered an Automation-as-a-Service model, handling design, implementation, hosting, monitoring, and maintenance to ensure the system’s reliability over time.

Ready to build your own workflow? Explore the Automation Template Marketplace for inspiration and pre-built workflows.

Solution Architecture & Workflow

The automation centers around a scheduled n8n workflow running every hour, orchestrating the end-to-end collection, processing, and follow-up on customer reviews.

Global Architecture Overview

• Trigger: Cron scheduler in n8n triggers workflow hourly.
• Orchestrator: n8n manages task orchestration, logic branching, API requests, and error handling.
• External Services Integrated: Gmail API – check for new review emails; Google Sheets API – update aggregated review log; HubSpot CRM API – enrich customer profiles; OpenAI API – review sentiment analysis and draft personalized replies.
• Outputs: Updated review dashboard in Google Sheets; automated thank-you emails; Slack notifications to Customer Success for flagged critical feedback.

End-to-End Workflow Walkthrough

1. Step 1: Trigger & Data Collection
   n8n cron node activates the flow every 60 minutes. The Gmail node queries new emails tagged as “Customer Review” in the inbox.
2. Step 2: Data Extraction & Validation
   Extract email content (review text, customer name, email), validate completeness, and deduplicate based on message IDs.
3. Step 3: Sentiment Analysis with OpenAI Agent
   Send review text to OpenAI Agent for sentiment scoring (positive, neutral, negative) and key topic extraction.
4. Step 4: Customer Data Enrichment
   Use HubSpot API to find or create customer records associated with the reviewer’s email, retrieving customer segment for marketing targeting.
5. Step 5: Update Google Sheets Repository
   Append new review records with detailed metadata, including sentiment score and timestamp, for visibility across teams.
6. Step 6: Automated Response Email
   Using OpenAI Agent generated personalized thank-you email drafts, the Gmail node sends replies automatically to reviewers.
7. Step 7: Notifications & Reporting
   Send Slack notifications for negative or critical reviews to Customer Success team for immediate attention.

Step-by-Step Node Breakdown 🚀

1. Cron Trigger Node

Triggers the workflow every 60 minutes with a simple cron expression. This allows continuous near-real-time collection without manual intervention.

2. Gmail: List and Filter Emails

Uses the Gmail API with a filter query of “label:CustomerReview is:unread” to retrieve new review emails. Fields mapped include email ID, subject, sender address, and body content.

3. Filter Node: Validate and Deduplicate

Filters out emails missing essential data (e.g., no review content) and checks Google Sheets for duplicate message IDs to avoid re-processing.

4. OpenAI Sentiment & Topic Analysis Node 🤖

Sends review text to OpenAI API for a sentiment score and key topics. Maps the input text from the email body, configures prompt templates for analysis, and extracts structured response fields.

5. HubSpot CRM Search/Update Node

Searches by email address to retrieve customer data. If no record exists, a new contact is created with tags indicating customer segment. Fields such as contact ID and segment are saved for later use.

6. Google Sheets Append Row Node

Adds a new row in the “Customer Reviews” sheet with columns: Timestamp, Customer Name, Email, Review Text, Sentiment, Topics, Customer Segment, and Follow-up Status.

7. Gmail Send Email Node

Sends a personalized thank-you note drafted by OpenAI to the customer’s email. Uses dynamic fields for the customer’s name and review summary, with fallback templates in case of API failure.

8. Slack Notification Node

Sends alerts to the Customer Success channel in Slack for any reviews marked as negative or critical. Includes review summary and a direct link to CRM records for rapid action.

Error Handling, Robustness & Security

Error Handling & Retries

The workflow includes automatic retry mechanisms with exponential backoff on API request failures, particularly for Gmail and OpenAI interactions. If a node fails repeatedly, the error is logged and an alert is triggered to Slack for immediate resolution.

Logging & Observability

All workflow runs are logged in n8n’s execution history and logged events sent to an external logging system for long-term storage and audits. Slack alerts notify the devops team on anomalies.

Idempotency & Deduplication

The system tracks each processed email by message ID in Google Sheets, ensuring no duplicate review is processed or responded to. This preserves data integrity and customer experience.

Security & Data Protection

• API Credentials: Stored securely using n8n encrypted credentials and environment variables with restricted access.
• Least-Privilege Scopes: Gmail and HubSpot API tokens have minimal scopes to access only required mailbox labels and CRM contacts.
• PII Handling: Customer information never leaves authorized systems; emails are deleted after processing per GDPR guidelines.
• Auditability: Workflow runs and data changes are auditable through system logs.

Performance, Scaling & Extensibility

Designed for scalable efficiency, the workflow can handle increasing volumes of review emails without degradation.

Queueing & Batching: For high volumes, review entries are batched before processing multiple OpenAI calls asynchronously to reduce API costs and latency.

Webhooks vs Polling: Initially polling Gmail every hour was used for simplicity. For higher SLAs, migration to push notifications via Gmail webhooks is feasible, providing near instant triggers.

Modular Workflow Design: Each logical component (data extraction, sentiment analysis, response sending) is modular, allowing updates or swapping out AI providers or CRM systems easily.

RestFlow Hosting: Managed hosting ensures that scaling infrastructure and workflow versions are handled automatically with minimal downtime.

Comparison Tables

n8n vs Make vs Zapier for Customer Review Automation

Option	Cost	Pros	Cons
n8n	Free self-hosted or $20+/mo RestFlow hosting	Open source, highly customizable, great API integrations, native code execution	Requires setup & maintenance; steeper learning curve
Make (Integromat)	Starts at $9/mo	Visual builder, rich library of integrations, simple conditional branching	Less flexible with complex custom code; costs grow with operations
Zapier	Starts at $20/mo	User friendly, extensive app support, good for simple automations	Limited complex branching & concurrency; higher per task cost

Webhook vs Polling for Email Trigger

Method	Latency	Resource Usage	Complexity
Polling	Up to polling interval (e.g., 60 min)	Moderate, periodic API calls	Simple to implement
Webhook (Push Notification)	Near real-time	Low continuous resource usage	Requires API/webhook setup and validation

Google Sheets vs Database for Review Storage

Storage	Simplicity	Scalability	Integration
Google Sheets	Very easy, familiar UI	Limited under large datasets & concurrency	Excellent native n8n integration
Database (PostgreSQL/MySQL)	Requires schema & admin skills	Highly scalable, ACID compliant	Integration via API nodes; flexible queries

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Results & Business Impact

The automated review collection workflow delivered immediate and significant ROI for the Brussels startup:

• Time Saved: Reduced manual review collection from 15+ hours to under 1 hour weekly, a >90% reduction in labor.
• Error Reduction: Eliminated data duplication and missing reviews with automated deduplication and validation.
• Speed: Customer thank-you emails sent within minutes of review receipt versus days before, boosting customer satisfaction.
• Visibility: Real-time Google Sheets dashboard enhanced cross-team transparency on feedback trends.
• Response Quality: AI-generated personalized replies improved brand engagement quality.

Marketing teams leveraged reliable review data for campaigns, and Customer Success quickly triaged critical feedback, improving overall customer experience [Source: internal client metrics].

Pilot Phase & Ongoing Maintenance Disclaimer

Upon deployment, the automation underwent an initial pilot phase running with live but carefully monitored data. During this stage, RestFlow’s team addressed minor bugs, edge cases with uncommon email formats, and optimized error handling.

Following successful pilot validation, RestFlow now provides ongoing hosting, monitoring, updates, and maintenance to ensure continuous smooth operation despite evolving data volumes or tool APIs. This approach guarantees the automation remains reliable and efficient as the business grows.

Frequently Asked Questions

Conclusion

This case study highlights how a Brussels-based SaaS startup successfully automated a manual, time-intensive customer review collection process using OpenAI Agents integrated with n8n, Gmail, Google Sheets, and HubSpot CRM. The solution delivered substantial time savings, improved data quality, and faster customer engagement.

RestFlow’s Automation-as-a-Service model provided a full spectrum of design, implementation, hosting, monitoring, and ongoing maintenance, ensuring the solution remains robust and scalable.

If you aim to replicate such automation success in your business, RestFlow offers powerful pre-built workflows and tailored expert services. Explore the Automation Template Marketplace to get inspired or Create Your Free RestFlow Account to start building your automation today.